Chapter 7.2, Problem 3aT

A wire is formed into a and the leads are twisted together. The sides of the loop are labeled A—D. The direction of the current is shown. (The diagram uses the convention that $\odot$ indicates current out of the page and $\otimes$ indicatescurrent into the page.)

1. On the top two diagrams at right, sketch magnetic field lines for the loop. Base your answer on your knowledge of the magnetic field of a current-carrying wire.

Explain why it is reasonable to ignore the effect of the magnetic field from the wire leads.

2. Consider the magnetic field of a bar magnet.

How are the magnetic field lines for the current loop similar to those for a short barmagnet?

Can you identify a “north” and a “south” pole for a current loop?

Devise a rule by which you can use your right hand to identify the magnetic poles of the loop from your knowledge of the direction of the current.